Cholera is racing along west and central Africa's rivers and trade routes, with active outbreaks in six countries and millions of children at risk, UNICEF has warned.

The waterborne disease is spreading faster than at any point in recent years, moving along two great river systems just as the Democratic Republic of Congo (DRC) – the country with the heaviest cholera death toll – fights the largest Ebola epidemic in its history. Behind both stands an accelerant that scientists increasingly name: a warmer, wetter, more disordered climate.

“This outbreak is no longer confined by borders,” said Gilles Fagninou, UNICEF's regional director for west and central Africa. “It is moving along shared rivers, trade routes and population movements, putting millions of children at risk.”

Two corridors, six countries

The outbreaks are strung along two routes. In the Lake Chad basin, a single Vibrio cholerae O1 Ogawa strain is moving between Chad, Cameroon and Nigeria. In the Congo river basin, the disease is linking the DRC, the Republic of Congo and the Central African Republic.

Nigeria has the region's biggest outbreak, with more than 50,000 cases and 338 deaths since January 1, driven by a surge in Borno state. The DRC has recorded the heaviest toll: more than 30,400 cases and nearly 700 deaths.

Flooding along both corridors is contaminating water, wrecking sanitation and cutting relief workers off from the communities that need them most. Children are carrying much of the burden. In the Central African Republic, under-10s account for 44% of reported cases; in Chad, nearly two-thirds of infections are in children under 15; in Cameroon the median patient is just 10 years old.

UNICEF is asking for a further $15mn to widen its response over the next six months, expanding access to clean water, strengthening surveillance and supporting oral cholera vaccination campaigns alongside the World Health Organization (WHO) and the Africa Centres for Disease Control and Prevention (Africa CDC).

A record Ebola outbreak

As cholera crosses those borders, the DRC is also fighting the worst Ebola epidemic in its history. The WHO recorded more than 3,600 confirmed cases and nearly 1,590 deaths as of July 30, a case-fatality rate of 44%, surpassing the 2018-2020 epidemic to become the country's largest on record and the fastest-spreading Ebola outbreak ever documented.

Declared on May 15, the outbreak is caused by the Bundibugyo strain, which has no licensed vaccine or approved treatment, and has spread across five provinces. By mid-July more than 80% of new infections were being picked up outside known contact lists, a sign that health teams were losing track of transmission chains.

“Ebola in eastern DRC is not a standalone event,” said Dr Tyler Evans, an infectious-disease specialist who worked the 2014-16 West African epidemic – the largest in history – and the 2018-20 DRC response. “It is sitting on top of armed conflict, mass displacement, malnutrition, measles, mpox, a fragile health system, and now a withdrawal of external support. The virus is the spark. The structural conditions are the accelerant.”

Evans warns that an outbreak of this size going undetected for months in the most Ebola-experienced country on earth says less about the pathogen than about the response systems dismantled before it arrived. Genomic work cited by his team points to a fresh animal-to-human spillover rather than a virus quietly circulating from an earlier outbreak, though the origin has not been formally confirmed.

The economic bill is climbing with the case count. The UN Development Programme (UNDP) has warned the outbreak could cost African economies up to $3.6bn and push almost one million people into poverty if it spreads. The Africa CDC and WHO are seeking $518mn for a six-month continental response.

The climate connection

A question hangs over both diseases: is a hotter planet making them worse? A growing body of research suggests it is, at least as an amplifier.

The WHO has already tied the global cholera surge to a changing climate. “Most of these larger outbreaks … is a direct impact of the increase in adverse climate,” the agency's cholera lead, Philippe Barboza, has said, pointing to floods, unprecedented monsoons and back-to-back cyclones. Vibrio cholerae thrives in warm water, and the heavy rain and flooding that UNICEF blames for the current spread wash sewage into drinking supplies.

A systematic review of 43 studies, published in Environmental Science and Pollution Research in 2020, found cholera incidence “highly attributed to climatic variables”, chief among them rainfall, air temperature and sea surface temperature.

The link runs wider than cholera. The IPCC's sixth assessment warned that ill health and premature deaths from climate impacts will rise sharply, with extreme weather already driving food and water insecurity across Africa. Warming is pushing vector-borne disease into places that once escaped it: yellow fever has climbed into Colombia's highlands, malaria killed more than 300 people in Zimbabwe in the first half of 2025, and mosquito-borne viruses are turning up far from their usual range.

Climate is not the whole story. Conflict, mass displacement, broken sanitation and, in Ebola's case, the syndemic Evans describes all feed these outbreaks. But the direction of travel is one way, and the warning from the epidemiologists is the same for both diseases: build the standing, locally led capacity now, before the next spark, rather than scrambling for money once the bodies are counted.